@Override
    public String toString() {
      return "CharMatcher.anyOf(\"" + showCharacter(match1) + showCharacter(match2) + "\")";
    }
  }

  /** Implementation of {@link #anyOf(CharSequence)} for three or more characters. */
  private static final class AnyOf extends CharMatcher {

    private final char[] chars;

    AnyOf(CharSequence chars) {
      this.chars = chars.toString().toCharArray();